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Old 05-09-2008, 11:07 PM   #20 (permalink)
Gregte
EcoModding Apprentice
 
Join Date: May 2008
Location: South Dakota
Posts: 117

GMC Sonoma - '94 GMC Sonoma
90 day: 36.97 mpg (US)
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Quote:
Originally Posted by toomuch View Post
Thanks for all the WAI feedback.
This warm air thing seems to have no one single answer.
Here is my current summation:
The greater the temp of the air, the lower the density.
Lower density air has less molecules per volume.
Less fuel is needed to keep the 14.7:1 ratio of air to fuel.
Also as was mentioned by one poster, warm air helps liquid gasoline to atomize, i.e. become a vapor, and only vaporized gasoline burns. To the extent that some of the gas is still liquid at the time of ignition, it is wasted.

My understanding is that there is a delicate balance with any given engine design regarding how warm the intake air should be; warmer for some, cooler for others.
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